Exploratory analysis of agro-morphological characteristics in Nigella sativa L. plant genotypes to determine mutagen colchicine ameliorative/ non-ameliorative impacts

This experimental study aimed to elucidate the optimal colchicine concentration for inducing polyploidy and to examine the morphological effects on Nigella sativa L. (family Ranunculaceae) plants recognized as 'Kalonji' in India. Here, seeds were exposed with different concentration of colchicine ranging from 0.025 to 0.4% with varying time duration (24-48 h). The agro-morphological attributes and chromosome counts of the putative polyploids were compared with control diploid plants, revealing significant differences. The ploidy level determined by chromosome counts revealed that 0.05-0.1% concentration of colchicine induced tetraploids within both plant genotypes for 24 h and 48 h. However, results based on agro-morphological trait correlation analysis revealed more significant association among yield traits at 0.1% concentration and the principal component analysis revealed that the maximum possible ameliorative effect of the colchicine dose was the lowest concentration (0.025% for a 48-hour exposure time) for the AN1 genotype; likewise, a 0.05% concentration established a more positive association in terms of growth and yield attributes for the AN20 genotype. This study demonstrated that low dosages (0.025% and 0.1%) strongly impact plant growth and yield, whereas higher dosages obliterate these positive effects and add destructive characteristics within plants which ultimately reduces yield.